Imperative role of SBS molecular structure on the performance properties of modified binders and asphalt mixes
Sk Sohel Islam, Sumit Singh, G.D. Ransinchung, Sham S. Ravindranath
Abstract
The current study evaluates the impact of SBS molecular structure (L-SBS, B-SBS, HV-SBS, and DB-SB) and concentration on asphalt mix performance. Polymers were characterized using GPC, FTIR, melt rheology, and DSC analysis. GPC analysis indicates that BSBS has the highest molecular weight, while DB-SB has the lowest. FT-IR studies show differences in vinyl content among the four polymers. Asphalt mixture study resonated binder study where B-SBS polymer outperformed their counterparts. Results showed that compared to widely used L-SBS polymer, B-SBS copolymer generates ≈ 33 %, 26 % and 18 % more fatigue resistance, rutting resistance and stiffness behaviour, respectively, at a polymer content of 4.5 wt.%. The combined effect of higher molecular weight, triblock structure and the long-chain branching in B-SBS copolymer contributes to the discussed outcome which facilitates its utilization for high-stressed pavement sections at upper and intermediate service temperatures. However, L-SBS and HV-SBS polymers depict almost similar mixture performance due to their alike molecular structure. Moreover, the presence of a di-block structure and lower molecular weight results in inferior performance for mixes prepared with DB-SB polymer. The results clearly signify the dominance of polymer molecular structure in identifying the mixes’ performance properties at respective polymer content.